Thyme is an ancient herb, used by the Greeks as a purifying incense. A low-growing perennial herb, thymes have woody stems and form a dense mat covered with tiny aromatic leaves and delicate blooms. Thyme plants require well-drained soil and full sun. Rich in essential oils, they are prized for their medicinal, as well culinary, uses. The entire thyme plant is attractive to wildlife, and all varieties make a wonderful and aromatic groundcover.